RU2541915C1 - Source of reference voltage determined through energy gap doubled width - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: device contains five transistors, three resistors and a current source which is coupled between the power supply bus and output terminal; the first resistor is coupled by its first output to the common bus, the second and third resistors are connected by their first outputs to the output terminal; bases of the first and the second transistors are connected to collectors of the first and fifth transistors and bases of the fourth and fifth transistors; the second output of the first resistor is coupled to emitter of the second transistor; emitters of the first and third transistors are connected to the common bus; collector of the third transistor is connected to the output terminal; the base of the third transistor is connected to collectors of the second and fourth transistor; emitter of the fourth transistor is connected to the second output of the second resistor; emitter of the fifth transistor is connected to the second output of the first resistor.

EFFECT: receipt of thermally stable output voltage, which value is close to doubled energy gap width of the used semiconductor.

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Description

The device relates to the field of electrical engineering and can be used as a temperature-stable source of reference voltage (ION).

Known temperature-stable sources of reference voltage, determined by the doubled band gap of the semiconductor, the disadvantage of which is the excessive complexity caused by the use of a large number of elements [U.S. Patent 4380706. Voltage reference circuit / Robert S. Wrathall. - Dec. 24, 1980], and the need for additional connection to a power supply source, and not just to a current source [Soklof S. Analog integrated circuits: Trans. from English - M .: Mir, 1988. - P.240, Fig. 33.27], which significantly complicates their use as a reference diode.

The closest technical solution adopted for the prototype is the ION shown in figure 1 [Patent RU 2488874 C1, IPC G05F 1/56; H03F 1/30 (2006.01). - Publ. 07/27/2013, Bull. No. 21]. The disadvantage of the prototype is the relatively high temperature drift of the output voltage (about 10 mV per 100 ° C).

The problem to which the invention is directed, is to provide the claimed technical result - reducing the temperature coefficient of the output voltage of the ion.

To achieve the claimed technical result, a prototype circuit comprising a current source connected between the power bus and the output terminal, a first resistor connected by the first terminal to the common bus, a second and third resistor connected by the first terminals to the output terminal, the first transistor whose emitter is connected to a common bus, a second transistor whose emitter is connected to the second terminal of the first resistor, a third transistor, whose collector is connected to the output terminal, and an emitter to a common bus, the fourth and fifth trans tori whose bases are connected, the collector of the fifth transistor is connected to the collector of the first and the bases of the first and second transistors, the emitter of the fourth transistor is connected to the second output of the second resistor, the emitter of the fifth transistor is connected to the second output of the third resistor, the collectors of the fourth and second transistors are connected to the base of the third transistor , introduced the connection of the base of the fourth transistor with the collector of the first transistor.

The prototype diagram is shown in figure 1. A diagram of the inventive device is presented in figure 2. Figure 3 shows the simulation results.

The inventive ION (figure 2) contains five transistors (first to fifth), respectively, indicated by numbers 1-5, and three resistors (first to third), indicated, respectively, by numbers 6, 7 and 8, and a current source 9, connected between the power bus and the output terminal, resistors 6 and 7 are connected by the first conclusions to the output terminal, the base of transistors 1, 2, 4, and 5 are connected to the collectors of transistors 1 and 5, a resistor 8 is connected between the common bus and emitter of transistor 2, emitters transistors 1 and 3 are connected to a common bus, the collector of transistor 3 is connected to output terminal, the base of transistor 3 is connected to the collectors of transistors 2 and 4, the emitter of transistor 4 is connected to the second output of the resistor 7, the emitter of transistor 5 is connected to the second output of the resistor 6.

Before you consider the operation of the claimed device, consider the operation of the prototype circuit (figure 1), as it is necessary for comparative analysis. In this case, let us assume that the base currents of the transistors are negligible, and there is no load current. The output voltage _{Uout of the} prototype is determined by the sum of the base-emitter _{voltages Ube3} and _{Ube4 of the} transistors VT3 and VT4, as well as the voltage drop U _R2 on the resistor R2, which can be described by the following expression:

where φ _t ≈26 mV is the temperature potential; I ₂ and I ₃ are the emitter currents of transistors VT2 and VT3, respectively; I _s is the saturation current of the reverse biased pn junction, proportional to its area; R ₂ is the resistance of the resistor R2.

To find the current I ₂ it is necessary to take into account the base-emitter voltage U _be1 and U _be2 , respectively, of transistors VT1 and VT2 and the voltage drop U _R1 on the resistor R ₁ , writing the expression:

or

where R ₁ is the resistance of the resistor R1; I ₁ is the emitter current of the transistor VT1; N is the ratio of the emitter areas of transistors VT2 and VT1.

The approximate relation (2) is valid when the currents I ₁ and I _{2 are} equal. From here you can determine the current

Differentiating expression (3), we can determine the dependence of the current increment I ₂ on temperature T:

where φ _t = kT / q; k is the Boltzmann constant; T is the absolute temperature; q is the electron charge.

Differentiating expression (1), we obtain

To find the increments dU _BE, one should take into account the dependence

where C is a constant coefficient determined by the production technology of the integrated transistor; E is the energy band gap at absolute zero, obtained by linear extrapolation from room temperature to absolute zero, equal to 1.205 V.

It can be shown that expression (5), taking into account (1), (3), (6), is reduced to the form

The first and second term in expression (7) are caused, respectively, by a change in voltages U _be3 and U _be4 .

Since the sum of the currents I ₁ , I ₂ and I _{3 is} constant, the increment dl ₃ = -dI ₁ -dI ₂ , and with equal currents I ₁ , I ₂ , I ₃ and the approximate equality of the increments dI ₁ and dI ₂ , taking into account (4), we obtain

Expression (7), taking into account (8), can be reduced to the following form:

Equating (9) to zero, we obtain a tuning condition under which the instability of the output voltage in temperature is close to zero:

The operation of the claimed device is similar to the prototype. However, the output voltage is determined by the sum of the voltages of the base-emitter of transistors 1 and 4, which is described by the following expression:

where R ₇ is the resistance of the resistor 7; I ₁ and I ₂ are the emitter currents of transistors 1 and 4, respectively.

The currents I ₁ and I ₂ are equal to the emitter current of the transistor 2 and are determined by the expression:

where R ₈ is the resistance of the resistor 8; N is the ratio of the emitter areas of transistors 2 and 1.

Differentiating expression (10), we can derive the equalities:

Differentiating expression (11), taking into account (6), (12) and (13), we obtain:

Where does the setting condition come from:

Comparing expressions (10) and (15), we can conclude that the temperature-stable output voltage is close to twice the band gap for both circuits. And since the voltage of the base-emitter of the transistor 3 practically does not affect the output voltage, the circuit of the claimed device provides higher stability of the output voltage than the prototype circuit.

Presented in figure 3, the simulation results reflect the dependence of the output voltage of the prototype (out1) and the inventive device (out2) on temperature. At the same time, for convenience of comparison, the voltage out2 is increased by 64 mV (lower diagram). The upper diagram shows the relative relative instabilities of the output voltage.

Thus, both the analysis and the data of circuit simulation confirm that the claimed technical result is achieved for the claimed device — a temperature-stable output voltage is obtained at values close to double the band gap.

Claims (1)

A voltage stabilizer comprising a current source connected between a power bus and an output terminal, a first resistor connected by a first terminal to a common bus, a second and third resistor connected by first terminals to an output terminal, a first transistor whose emitter is connected to a common bus, a second transistor, the emitter of which is connected to the second terminal of the first resistor, the third transistor, the collector of which is connected to the output terminal, and the emitter to the common bus, the fourth and fifth transistors, whose bases are connected, the collector is fifth the transistor is connected to the collector of the first and the bases of the first and second transistors, the emitter of the fourth transistor is connected to the second terminal of the second resistor, the emitter of the fifth transistor is connected to the second terminal of the third resistor, the collectors of the fourth and second transistors are connected to the base of the third transistor, characterized in that the base of the fourth transistor connected to the collector of the first transistor.

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